The workpiece grippers of manipulating devices, or respectively robots, must be individually matched to the workpieces. In connection with sheet metal parts, for example for motor vehicles, they normally have the form of a tube-shaped boom of, for example, 2 m length, with several boom extensions, to which suction grippers and/or clamping grippers are attached. Since the sheet metal parts are being deformed in several stamping presses, which are linked with each other, until they have their final shape, and since a specially designed workpiece gripper in accordance with the respective intermediate stage is required for a transfer to the next stamping press, 120 different workpiece grippers are required in order to produce 20 different sheet metal parts for a defined vehicle model on a line with, for example six stamping presses. So that the stocks of sheet metal parts can be kept as low as possible, the press tools are mostly exchanged in the course of only a few hours. Accordingly, in one work day it is often necessary to change the workpiece grippers of all transfer robots at the stamping presses ten times.
There are simple connections, which can be manually made by attachment screws, between the boom of a workpiece gripper and the portion of the robot supporting it, which is driven in a controlled manner. However, in view of the very high capital cost of a stamping press line per unit of time, a rapid exchange of the workpiece grippers must be relied upon. This requires quick acting couplers, which are motor-actuated when automatic gripper changing systems are used.
Such known couplers of this kind typically consist of a housing-like fixed element on the drive side, into which a matched connecting element coupled with the boom can be inserted and locked in place by means of interlocking connecting elements, for example stop bolts or hooks extending behind transverse pins. Since all workpiece grippers must be equipped with such a connecting element, considerable total costs result because of the multitude of grippers.